When storage drives which use flash memories (such as flash drives) are used as storage media for a storage apparatus and if the number of times of data write exceeds an upper limit value, the storage devices no longer operate properly and it becomes necessary to replace the storage devices as they have reached the end of their lives. Therefore, data are distributed and written to a plurality of storage devices, thereby lengthening the lives of the individual storage devices and the life of the entire storage system including the storage devices.
However, if data are distributed and written to the plurality of storage devices, the lives of the respective storage devices are equalized, thereby resulting in a situation where the plurality of storage devices need to be replaced at the same time; and since a plurality of processing sequences for dynamic sparing occur as processing for saving data stored in each storage device, which is a target to be replaced, to a spare storage device, so that performance of the storage system degrades.
Incidentally, Patent Literature 1 discloses a technique that prevents a plurality of storage media from reaching an upper limit of the number of times of write at the same time by replacing a normal disk with a spare disk as the need arises.